Love Your Skin (Protection from Harmful Ultraviolet Rays)

By Stephen Paul, Ph.D. Temple University

Protecting yourself from the sun’s rays comes in many different forms.  These basic sun-protection principles include applying sunscreens, wearing protective clothing, seeking out areas with substantial environmental shade, staying inside on very hot and humid days, and avoiding peak sunshine hours from 10 a.m. to 4 p.m., protecting the eyes with wrap-around sunglasses or sunglasses with side panels, and wearing a broad-brimmed hat to protect the ears, eyes, face, and neck.  For good measure, always remember to hydrate with the proper fluid, especially when in the sun and heat.

99.9% of all runners violate these principles that the health community professionals try to convey to us.  These guidelines are critical to avoid being the 1 in 5 runners whose skin damage will lead to some form of skin cancer.

Electro-Magnetic Spectrum and Light

This blog will focus primarily on just a portion of Principle Number 1: Sunscreens.  In order to understand the fortification or lack of protection from ultraviolet radiation (UV) it will be very helpful to have the knowledge of the electro-magnetic spectrum and light. (Figure 1,  Electro-Magnetic Spectrum) 

Figure 1 Electro-Magnetic Spectrum and Light

There are known-knowns, details we understand.  There are also known-unknowns; features about the non-visible spectrum that we have yet to comprehend.  Lastly, there are also unknown-unknowns, the aspects of the entire spectrum and light that have not been uncovered that could impact all living things.  It is this last category that can be the most challenging as we continue to learn about our planet undergoing climatic changes and its impact on health, food production, and biodiversity.  The biggest challenge facing us is to determine what is real news and what is fake news.

There is adequate data indicating that parts of the electro-magnetic spectrum and light are hazardous to our well-being.  This spectrum of gamma rays, x-rays, ultraviolet rays, visible light and infrared, rays can be hazardous to our health depending on the cumulative exposure time.  These categories are similar forms of rays (radiation) or electromagnetic (EM) energy.  Humanoids are able to sense a portion of the band of radiation through sight, feel, and touch (infrared rays).  Infrared radiation, in microwave ovens, is the energy that cooks food.

Figure 2 Radiation Levels Influenced By Many Factors

Figure 2 shows how ultraviolet rays are influenced by many factors.  The radiation destructive power is impacted by the angle of the sun in the sky and the actual location of the runner.  The rays are the strongest when the sun is directly overhead.  Radiation levels also vary with the hour of day and the seasons of the year.  The actual location of each runner is determined by their latitude and longitude position on our planet.  Latitude is the angular distance of the runner’s whereabouts north or south of the Earth’s equator.  This is usually expressed in degrees and minutes.  Longitude is the other half of the runner’s ability. to be located at any time.  Longitude is the distance measured in degrees east or west from an imaginary line (called the prime meridian) that goes from the North Pole to the South Pole and that passes through Greenwich, England.  The prime meridian is 0° (zero degrees), and the farthest away is +180° eastward and -180° westward) from the English city of Greenwich.


The combination of Latitude and Longitude is just like being able to be located by GPS (Global Positioning System).  GPS is a more sophisticated navigation system to determine the ground position of any object.  GPS from smartphones is typically accurate to within a radius of 16 feet under an open sky view.  Its accuracy is less reliable near buildings, bridges, and trees.

Ultraviolet Radiation (Rays)

Radiation levels are at their maximum when the sky is devoid of clouds.  Cloud cover does not offer an adequate shield. 

Figure 3 UV A, UV B, and UV C Penetration of Earth

Ozone is a chemical compound that consists of three oxygen atoms.  It appears in numerous documents as O3 or O3. The ozone cover provides a level of protection.  UV C for example, would reach the surface of our planet if the ozone layer was not there.  This can be seen in Figure 3:  UV A, UV B, and UV C Penetration of Earth and Figure 4,  Layers of Ozone. 

Figure 4 Layers of Ozone

The problem is that the ozone thickness can vary across the day, over the year, and as well as its planetary coverage.  UVC is stopped by the ozone layer completely.  UVA will penetrate the ozone layer.  UVB radiation is partially blocked by stratospheric ozone.  Both UVA and UVB are thwarted by surface-level ozone (SMOG) created by air pollution in the troposphere.  UV A and UV B can be blocked by broad-spectrum sunscreens.

Figure 5 Ozone-Oxygen Cycle in the Ozone Layer

The Figure 5 diagram illustrates the ozone-oxygen cycle that was created by NASA (National Aeronautics and Space Administration).  This shows the dynamic changing nature of the relationship between ozone and oxygen.

Skin Cancer

Contrary to what many runners and outdoor enthusiasts believe, the facts show that the most common type of cancer in America is that of the skin.  This cancer impacts differently on each of the traditional male and female sex categories as we age.  I have not seen any studies on the breakout of the newer classifications of gender and sexuality populations.  Different social-media organizations can use various definitions and numbers of preferences that are too numerous to mention.  Try looking up gender identity, sexual orientation, or gender and sexual identities to see what you find.

There are three types of skin cancer—squamous cell and basal cell are caused by total exposure to sunlight.  Each exposure to direct sunlight on the part of the skin adds to the damage you have received from birth.  Melanomas are different.  They can be caused by a single sunburn or many radiation insults at any age.

Left undefended, ultraviolet A (UVA) and ultraviolet B (UVB) radiation damage, will result in precancerous areas on our bodies called actinic keratoses (AK).  These growths are common in fair-skinned individuals and more runners who are frequently in the sun.  AK starts to show up after years of exposure to the sun.  If untreated, AK can progress to a solitary or supplementary skin cancers known as squamous cell carcinoma (cancer).  Fresh skin cancers like basal cell carcinoma and melenoma do not have to start with AK.

All skin cancers are highly curable with early detection and correct treatment.  The five-year survival for individuals with early melanoma detection and treatment before it spreads to the lymph nodes is 99%.  If melanomas spread (metastases to regional or more distant sites) the cure rate is significantly reduced. (American Cancer Society Cancer Facts & Figures 2019)

Basal cell carcinoma (BCC) is frequently seen in runners of all races and skin tones from very light and extremely dark.  Therefore, all runners should use body protection.  In addition to the American Cancer Society, Excellent information is also available at: (

Principle Number 1


Do you apply sun screen on all skin areas that are exposed to the sun?  Do you know that sun exposure to the ultraviolet rays creates cumulative damage to the skin over many years resulting in wrinkly and weather-beaten leather-like skin?  This damage also prematurely ages this largest organ of the body.

Figure 6 Sunscreen Protection From UV A and UV B

Sun screens should be applied at least 15 minutes before you go out the door on sunny, cloudy, or wintery days since the rays are always reaching our Earth.  The role of waiting that time is to allow the application to be fully absorbed into the skin for maximum protection.

Sun Protection Factor

The sun protection factor (SPF) is a method measuring the length of time that the product protects against sunburn.  Redness represents the first level of visible skin damage.  This is why some products provide protection for a maximum of 40 minutes while other merchandise can give a level of safety for 80 minutes.  Any item that is labeled “broad spectrum” must protect against UV A and UV B.  The government does not yet rate the efficiency of the protection.  You can look at the rating as a pass or fail. 

Sun screen products can be classified into three categories. Mineral or physical products contain either zinc oxide, titanium, or both.  Zinc Oxide is a protectorant from UVB and UVA.  As you can see in  Figure 6, Sunscreen Protection from UV A and UV B perform their function differently.  The second grouping are chemicals that are not found naturally.  The last category are products that combine some of both classifications.


The forthcoming blog will continue with the Principles of protection against skin cancer.  In the meantime, make an appointment with your health-care professional if you notice a new spot or an existing area that changes in size, shape, color, itches, or bleeds.  Have that individual check to see if it might be AK or something more problematic.

REMEMBER, the best type of sunscreen for you is the one used and applied correctly.

Categories: Product Reviews

2 replies

  1. Very well written article.


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